1. Field of the Invention
The present invention relates to a foldable table frame for supporting a machine set thereon, more particularly to a foldable table frame which occupies a relatively small amount of space when folded.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a known table frame 20 for supporting a machine set (not shown) thereon is shown to include a rectangular tabletop unit 21 and a foldable leg unit 22. The tabletop unit 21 is mounted horizontally on top of the leg unit 22 when the latter is unfolded. The tabletop unit 21 includes front and rear rods 211 and a pair of lateral rods 215 interconnecting the front and rear rods 211. The leg unit 22 includes X-shaped front and rear leg frame portions 221 mounted on the front and rear rods 211, respectively, and a pair of linking rods 225 interconnecting the front and rear leg frame portions 221. Each of the front and rear leg frame portions 221 has leg members 223 disposed in a criss-crossing arrangement and pivoted to each other at middle sections thereof. Each of the leg members 223 has an upper end pivoted to a corresponding one of the front and rear rods 211 using a respective pivot axle 222 that extends through a respective elongated slot 212 formed in the corresponding one of the front and rear rods 211. The pivot axle 222 is slidable along the slot 212 during folding and unfolding operation of the table frame 20. Each of the front and rear rods 211 has an inner side provided with a retaining plate 23 which is biased to move downwardly and which has a bottom edge formed with a pair of notch sets, each including a first notch 231 for engaging a corresponding pivot axle 222 when the leg unit 22 is folded so as to retain the leg unit 22 in a folded position, and a second notch 231xe2x80x2 for engaging the corresponding pivot axle 222 when the leg unit 22 is unfolded so as to retain the leg unit 22 in an unfolded position. The retaining plate 23 is formed with a handle extension 232. In use, the handle extensions 232 are lifted upwardly to disengage the retaining plates 23 from the pivot axles 222 so as to permit folding and unfolding of the leg unit 22.
However, it is noted that the conventional table frame 20 has a relatively large thickness when the leg unit 22 is folded upon the tabletop unit 21. Moreover, since the tabletop unit 21 is unfoldable, the conventional table frame 20 still occupies a relatively large amount of space in its folded state.
Therefore, the main object of the present invention is to provide a foldable table frame which has a reduced thickness and which occupies a relatively small amount of space when folded. Accordingly, the foldable table frame of the present invention includes a tabletop unit and a leg unit. The tabletop unit includes front and rear frame members, each of which has a U-shaped configuration. The front frame member includes parallel first lateral rods with front and rear ends and a horizontal front bar extending transversely between the front ends of the first lateral rods. The rear frame member includes parallel second lateral rods with front and rear ends and a horizontal rear bar extending transversely between the rear ends of the second lateral rods. Each of the front and rear frame members has a top wall. The rear ends of the first lateral rods of the front frame member are connected pivotally and respectively to the front ends of the second lateral rods of the rear frame member such that the front and rear frame members are pivotable relative to each other about a horizontal upper pivot axis parallel to the front and rear bars. Each of the first and second lateral rods of the front and rear frame members has a bottom side formed with a recess. The rear end of each of the first lateral rods has an end plate, which has a convex edge. The front end of each of the second lateral rods has an end piece which is pivoted to the end plate of the respective one of the first lateral rods for pivoting about the upper pivot axis and which has an abutment portion that is transverse to the end plate of the respective one of the first lateral rods. The table top unit is movable between an unfolded position, in which the top wall of the front frame member extends horizontally and is coplanar with the top wall of the rear frame member, and a folded position in which the first and second lateral rods are turned upright to enable the front and rear bars to move proximate to each other. The convex edge on the rear end of each of the first lateral rods moves along the abutment portion on the front end of the respective one of the second lateral rods during movement of the front and rear frame members between the folded and unfolded positions. The leg unit includes a pair of X-shaped leg frame portions, each of which includes first and second leg members having upper and lower ends and intermediate sections pivoted to each other about a lower pivot axis that is located below and that is parallel to the upper pivot axis. The upper ends of the first leg members of the leg frame portions are pivoted respectively to the first lateral rods of the front frame member about a horizontal front pivot axis parallel to the upper pivot axis. The upper ends of the second leg members of the leg frame portions are pivoted respectively to the second lateral rods of the rear frame member of the tabletop unit about a horizontal rear pivot axis parallel to the front pivot axis. The first and second leg members of each of the leg frame portions are movable together with the first and second lateral rods, and pivot relative to each other about the lower pivot axis for folding toward and for unfolding from each other when the tabletop unit is moved between the folded and unfolded positions. The first and second leg members of the leg frame portions extend respectively into the recesses of the first and second lateral rods of the front and rear frame members of the tabletop unit when the tabletop unit is moved to the folded position.